The present disclosure relates to a new method for folding a filter bag to facilitate installation in a filter retaining basket of a bag filter unit and the folded filter bag arrangement.
When removing a used filter bag from a liquid bag filter unit and replacing it with a new filter bag, the operator must make certain to install the new filter bag so that the bottom of the clean filter bag is in contact with the bottom of the filter retainer basket. Failure to do so can cause a filter bag to burst during normal operation of the filter unit, due to differential pressure across the unsupported bag media.
When filter bags are made of a stiff filter media, such as a nonwoven fabric or a polymeric material, and have seams which may be sewn, ultrasonically welded or hot gas welded, the operator may have a difficult time installing the new filter bag with the assurance of a proper, secure fit. This is largely due to a mismatch in geometry between the bag and basket. A filter bag contains a bottom seam that is welded or sewn while the filter bag is flat as opposed to the cylindrical shape of the filter retainer basket. This mismatch may require bag positioners or installation tools for proper supported installation.
Thus, there still exists a need for a folded filter bag arrangement to facilitate installation of a filter bag in a filter unit when replacing a filter bag, and a method for making drop-in filter bag easily installed when it is time for replacement, and eliminate the need for bag positioner or special installation tools.